Field of the Invention
The invention relates to a liquid crystal display (LCD) and an image-dithering compensation method thereof.
Description of the Related Art
In the conventional image-dithering compensation method, a blending-like method is adopted to change the gray scale value having low bits into the gray scale value having high bits in a spatial domain and/or or in a temporal domain, which is not easily perceived by the human eye. The input image data having low bits is received and the output image having high bits is displayed.
FIGS. 1A and 1B are schematic views showing the conventional image-dithering compensation methods. FIG. 1A shows the conventional image-dithering compensation performed in the temporal domain, while FIG. 1B shows the conventional image-dithering compensation performed in the spatial domain.
As shown in FIG. 1A, a pixel array 102 includes 2×2 pixels. When the image-dithering compensation is performed, it is supposed that for example, the pixel array 102 has 0, 1, 2, 3 and 4 black pixels in five continuous frames, respectively. In this case, in the temporal domain, the human eye feels like that the color of this pixel array gradually changes from white 110, three different grays 112 to 116 (with different darkness values) to black 118 in the five continuous frames, wherein the gray 116 has the darkness color, and the gray 112 has the lightest color.
FIG. 1B is directed to the visual effect seen by the human eye when the human eye sees several neighboring pixels in the same frame. Herein, four neighboring pixels 122A to 122D are described as an example. If the pixels 122A to 122D are white (i.e., the first row of FIG. 1B), then the visual effect of the human eye recognizes that the overall color of the four pixels 122A to 122D represents the white 130, and so on. With the image-dithering compensation of FIG. 1B, the four neighboring pixels, which originally show two colors (black and white), represent five colors (white 130, grays 132 to 136 and black 138).
In order to improve image display, a digital gamma correction has been proposed to independently control the R/G/B gray scale values of each pixel/sub-pixel and to independently control the polarity of each pixel/sub-pixel.